Objective: This proposal is for a CDA-2 mentored training program that will transition Alan Teo, MD, MS into an independent VA mental health services researcher who has special expertise in the role of Veterans' social relationships in influencing mental health outcomes. The overarching objective of the research plan is to inform development of an intervention for primary care patients with major depression that harnesses the positive influences of close relationships on Veterans' depression care. Research Plan: Dr. Teo will conduct three sequential studies using mixed methods. The research approach will draw upon the literature on social support, social networks, and social cognitive theory. The Specific Aims of the proposed research are to: 1) Determine which features of VA patients' close relationships are associated with depression-related behaviors and outcomes; 2) Assess perceptions of key stakeholders in Veterans' depression treatment in primary care, including Veterans, their close relations, and clinicians involved in primary care-mental health integration; and 3) Develop and test a pilot intervention that promotes effective engagement of close relations in the care of VA primary care patients with major depressive disorder. Methods: The Aim 1 study will be a prospective cohort study of 200 primary care patients with depression to identify to what extent three social processes (social support, interpersonal conflict, and social norms) are associated with depression-related health behaviors, depression severity, and suicidal ideation and behaviors. A combination of cross-sectional and longitudinal analyses will be conducted, and results will support preparation of an IIR proposal. The Aim 2 study will be qualitative, employing interviews and focus groups. Results will provide a nuanced description of how close relations perceive Veterans' depression, existing ways that close relations are involved in Veterans' depression care, and preferences, barriers, and facilitators around engagement of close relations in Veterans' depression care. Finally, Aim 3 will be the development of a pilot intervention that will be tested locally in a non controlled trial. Intervention development will incorporate the most promising strategies identified by results from Aim 1 and Aim 2. Evaluation will focus on acceptability and feasibility. The expected outcome will be a manualized intervention and preliminary data to support a proposal for a larger randomized controlled trial. Participatory research methods involving Veterans and their close relations will be used in the Aims 2 and Aim 3 studies. Career Plan: Dr. Teo is a physician-investigator with training in health services research methods and expertise in social support and depression treatment in primary care settings. This proposal will substantially deepen his theoretical understanding, content expertise, and research skills. Specific areas for training are: 1) Qualitative and advanced quantitative skills that can be applied to mixed methods approaches in health services research; 2) Social relationship theory and applications to mental health; and 3) Intervention development for depression and suicide. The training plan will consist of formal coursework, seminars, and readings guided by the mentorship team. Ultimately, these efforts will assist in Dr. Teo reaching his goal of becoming a national leader in conducting research and implementing practice that integrates consideration of patients' social context into delivery of their mental health care.